Non-reuseable hypodermic syringe
TECHNICAL FIELD 
     The present invention relates to a medical device, and more particularly to a hypodermic syringe which can only be used only one time to inject a patient or a user with a liquid. 
     BACKGROUND OF THE ART 
     The spread of blood- or fluid-borne communicable and contagious diseases, such as Acquired Immune Deficiency Syndrome (AIDS), infectious hepatitis, syphilis and the like, continues to be of grave epidemiological concern. Of particular concern is the spread of AIDS and hepatitis among intravenous (IV) drug-users. It has been broadly estimated that more than half of the incidence of AIDS in an urban population center, e.g., New York City, may be directly attributed to intravenous drug use, i.e., the sharing or exchange of needles among IV drug users. 
     The incidence of AIDS among IV drug users has become so widespread that public health authorities are advocating the free distribution of clean needles to addict drug users. 
     It is clearly apparent that a means to limit the use of hypodermic needles to only a single injection in a patient or user would be highly desirable to slow the spread of contagious blood diseases, e.g., AIDS and hepatitis. 
     DISCLOSURE OF THE INVENTION 
     The present invention is directed to a hypodermic syringe which, because of its features, can be used for only one injection of liquid, and thereafter the syringe cannot be used again to inject a patient or user. 
     A principal embodiment of the present invention is directed to a hypodermic syringe comprising (a) a hollow barrel for containing liquid and having a needle hub means, a cover joining means, and a rear open face, said needle hub means adapted to form a holder for a needle to inject liquid from within the barrel through a needle; (b) a longitudinally slidable and axially rotatable plunger shaft having a body, a rear end and a front end, said front end of said shaft positioned within said barrel, said rear end of said shaft positioned outside of said barrel, said rear end of said shaft being adapted to move said shaft longitudinally within the barrel; (c) a cover having an open face and including (i) charging positioning means for longitudinally moving the shaft within the barrel between (I) a first charging position where the front end of the shaft and the needle hub of the barrel are substantially aligned together to (II) a second charging position where the front end of the shaft is longitudinally displaced within the barrel from the needle hub; (ii) axial rotational means for rotating the shaft of about 180° to a plurality of discharge positions when the shaft is in (II) the second charging position; and (iii) discharging positioning means for longitudinally moving the shaft within the barrel where the plurality of discharge positions are selected from the group of positions between a first discharging position where the front end of the shaft and the rear open face of the barrel are substantially aligned to a second position where the front end of the shaft is longitudinally displaced from the rear open face of the barrel, said cover being integrally joined to said cover joining means of said barrel; and (d) a sealing means for preventing the leakage of liquid between the front end of the shaft and the rear open face of said barrel or for preventing the introduction of air into the liquid. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings of illustrative embodiments of the invention in which 
     FIG. 1 is a sectional view showing the hypodermic syringe of the present invention prior to use, i.e., prior to &#34;charging&#34; or filling the syringe barrel with liquid. 
     FIG. 2 is a perspective cutaway view of the plunger shaft removed from the barrel of the hypodermic syringe. 
     FIG. 3 is a top view of the cover of the hypodermic syringe. 
     FIG. 4 is a front view of the top cover of the hypodermic syringe. 
     FIG. 5 is a sectional view showing the hypodermic syringe of FIG. 1 &#34;charged&#34; or filled with liquid prior to injection into a patient. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIG. 1, the hypodermic syringe of the present invention has as a first component a hollow barrel 10 for containing liquid and having a rear open face 15, a flanged surface 85, and a needle hub 20. The needle hub 20 is adapted into an injection port 25 and is also adapted to form a holder for a needle (not shown) to inject liquid from within the barrel 10 through the needle. The hollow barrel 10 further comprises an inner barrel wall 30. 
     The hypodermic syringe has as a second component a longitudinally moveable (slidable) and axially rotatable plunger shaft 35 extending partially through the hollow barrel 10. The plunger shaft 35 has a body 37, a rear end 40 and a front end 45. The rear end 40 is positioned outside of the barrel and is adaptable to move the shaft 35 longitudinally within the barrel 10. The front end 45 is positioned within the inner barrel wall 30 and is further adapted to attach a sealing gasket (self re-sealing rubber cap) 75 for preventing the leakage of liquid between the shaft and out the rear open face of the barrel. A support stopper 80 is also shown in FIG. 1 and secures the attachment of the sealing gasket 75 to the front end 45 of the shaft. 
     As also shown in FIG. 1, the plunger shaft 35 additionally comprises at least one locking groove 50 which is positioned on the body 37 of the shaft 35. The plunger shaft 35 additionally comprises a longitudinal slot 55. In other embodiments a longitudinal guide 60 is provided on the body 37 of the shaft 35. 
     The hypodermic syringe has as a third component a cover 62 having an open surface and integrally joined to the flanged surface 85 of the barrel 10. 
     The cover 62 may be integrally joined to the flanged surface 85 of the barrel 10 using methods well known to those skilled in the art. A preferred method of joining the cover to the flanged surface of the barrel uses an energy director and is called ultrasonic welding. An apparatus used for that purpose is referred to as an ultrasonic welding machine and is available from Bronson (Hartford, CT). 
     As shown in FIG. 1, there are two members positioned directly across from each other on the cover 62 for longitudinally moving the plunger shaft 35 within the barrel 10, and by consequence, charging or discharging of liquid within the barrel 10 through the injection port 25. The charging releasing member 65 longitudinally moves the plunger shaft 35 within the hollow barrel 10 between (I) a first charging position where the front end of the shaft and the needle hub of the barrel are substantially aligned together to (II) a second charging position where the front end 45 of the plunger shaft 35 is longitudinally displaced within the barrel from the needle hub 20 and injection port 25. The discharging releasing member 70 longitudinally moves the plunger shaft 35 within the hollow barrel 10 between a first position where the front end 45 of the shaft 35 and the needle hub 20 of the barrel 10 are substantially aligned to a second position where the front end 45 is longitudinally displaced from the rear open face 15 of the hollow barrel 10. 
     As shown in FIG. 1, the charging release member 65 is aligned with the locking grooves 50 and the discharging release member 70 is aligned with the longitudinal slot 55. As also shown in FIG. 1, the charging release member 65 and the discharging release member 70 each includes an outer surface 102 and 105, respectively, and an inner surface, 110 and 115, respectively. 
     In FIG. 1, the charging release member 65 is attached to the cover 62 proximate to the rear open face 15 of the barrel. The discharging release member 70 is also attached to the cover 62 and is 180° across the cover opening from the charging release member 70. 
     The charging release member 65 is adapted to provide a unidirectionally flexible point 120 which will longitudinally move the plunger shaft 35 within the hollow barrel 10 between (I) a first charging position where the front end of the shaft 35 and the needle hub 20 of the barrel 10 are substantially aligned together to (II) a second charging position where the front end of the shaft 45 is longitudinally displaced within the barrel from the needle hub 20 and injection port 25 when the locking groove or grooves 50 are aligned with the charging release member 65. When any of the locking grooves 50 move past the unidirectionally flexible point 120 as the front end 45 of the plunger shaft 35 is longitudinally displaced from the needle hub 20 and injection port 25, the return (or reverse movement) of the locking grooves 50 past the unidirectionally flexible point 120 of the charging release member 65 and of the longitudinal displacement of the front end 45 of the plunger shaft from the rear open face 15 of the hollow barrel 10 will be prevented. 
     The discharging release member 70 is also adapted to provide a unidirectionally flexible point 125. As shown in FIG. 1, the longitudinal slot 55 is substantially aligned with the discharging release member 70. In such an alignment, there is no obstruction of longitudinal movement vis-a-vis the longitudinal slot 55 and the discharging release member 70. 
     The longitudinal guide 60 rotates the plunger shaft 35 of about 180° to a plurality of discharge positions when the shaft is in (II) the second charging position. The (II) second charging position has been reached where the front end 45 of the shaft 35 cannot be further longitudinally displaced within the barrel 10 from the needle hub 20. In a preferred embodiment, the longitudinal guide 60 is positioned midway between the locking grooves 50 and the longitudinal slot 55 as shown in FIG. 2. 
     In FIG. 2, there is provided a perspective cutaway view of the plunger shaft 35 removed or isolated from the hollow barrel 10 of the hypodermic syringe. This perspective shows the plunger shaft 35, the body 37, rear end 40 of the shaft, locking grooves 50, longitudinal guide 60, conical end marker 95 with support stopper 80 for the sealing gasket (not shown). 
     FIG. 3 is a top view of the cover 62 of the hypodermic syringe of the present invention. The charging release member 65 and discharging release member 70 are shown in FIG. 3 positioned diametrically across from each other on the cover 62. Also shown are a first guide notch 72 and a second guide notch 73 also positioned diametrically across from each other on the cover 62 and each approximately midway between the charging release member 65 and the discharging release member 70. Each guide notch 72 and 73 is adapted to secure the longitudinal guide 60 in place before or after axial rotation of the plunger shaft 35. The first guide notch 72 is adapted to secure the longitudinal guide 60 in place when the hypodermic syringe is being charged from (I) a first charging position to (II) a second charging position. After the shaft has been axially rotated 180°, as shown in FIG. 5, the second guide notch 73 secures the longitudinal guide 60 in place. The dotted line shown in FIG. 3 represents the outline of the hollow barrel 10 to which the cover 62 is integrally joined according to the present invention. 
     FIG. 4 is a front view of the top cover 62 of the hypodermic syringe of the present invention. In FIG. 4 is shown the charging release member 65 and discharging release member 70. Also shown are the unidirectionally flexible points, 120 and 125, of the respective release members, 65 and 70. In addition, the longitudinal guide 60 of the plunger shaft is shown in FIG. 4. 
     FIG. 5 is a sectional view showing the hypodermic syringe of FIG. 1 after it is charged with liquid prior to injection into a patient. 
     The plunger shaft 35 has been axially rotated 180° in FIG. 5 so that the locking grooves 50 are substantially aligned with the discharging release member 70 and the longitudinal slot 55 is substantially aligned with the charging release member 65. From the position as shown in FIG. 5, the plunger shaft 35 may be longitudinally moved within the hollow barrel 10 so that the front end 45 of the plunger shaft is longitudinally displaced from the rear open face 15 of the hollow barrel. As the plunger shaft 35 moves longitudinally within the hollow barrel 10 by the longitudinal displacement of the front end 45 from the rear open face 15, liquid is pushed through the injection port 25 and any needle placed over the needle hub 20. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.